This project has been directed at understanding and manipulating mechanisms of cell-mediated immune cytotoxicity. Long-range goals are: 1) to identify and characterize factors which influence induction, maturation, and expression of a cellular immune response; 2) to define changes in cellular immunity which occur in tumor-bearing hosts; 3) to find means of manipulating the cellular immune response for therapeutic purposes. Immediate objectives of the past year have been to concentrate on goals 2 and 3.